The present invention is directed to a method for the production of decorative laminates which are employed in conjunction with a substrate such as particle board for use in countertops, furniture and the like.
In making decorative laminates, a plurality of sheets are impregnated with a thermosetting resin and stacked in superimposed relation with a decorative sheet placed on top. This assembly is then heat and pressure consolidated. Generally, more than one laminate is formed at one time by inserting a plurality of sheet assemblies in a stack with each assembly being separated by a release medium which allows the individual laminates to be separated after heat and pressure consolidation.
The laminates so formed are then bonded to a substrate such as plywood, hardboard, asbestos board, particle board, and the like by the use of adhesives such as contact adhesives, urea-formaldehyde, white glues (polyvinyl acetate emulsions), hot melts, phenolic or resorcinol formaldehyde, epoxy, coal tar, animal glues and the like.
It has been found to be desirable during the production of such laminates to impart to the decorative surface portion of the laminate abrasion-resistant characteristics to enhance the utility of such laminates as table and countertops, wall panels and floor surfacing. Such abrasion resistance has in the past been imparted to decorative laminates having a printed decorative sheet by means of an applied overlay sheet which provided a transparent barrier over the decorative print sheet. Resin coatings have also been applied to the surface of the laminate which coatings contain abrasion-resistant mineral particles. Note in this regard U.S. Pat. Nos. 3,135,643; 3,373,070; 3,373,071; 3,798,111; 3,928,706; 4,255,480; 4,263,081; 4,305,987; 4,322,468; 4,327,141; 4,395,452; 4,400,423; and 4,430,375.
The above-noted methods, while generally providing satisfactory results, are undesirable in that they require either the use of additional materials (i.e., the overlay sheet) or the use of additional coating steps. Such disadvantages result in lessened efficiency and cost-effectiveness of the abrasion-resistant characteristics thereby provided.